Who Was Petri? 



Ralph C Benedict 



For presenting the sul)ject of bacteria to high school classes 

 in h>giene and biology, the most indispensable piece of appar- 

 atus is the Petri dish. But, — who was Petri? And when and 

 why did he in\-cnt tiie dish which goes by his name? 



Probabi\- many a teacher, in introducing his pupils to the 

 experimental stud\' of germs, has made some casual reference 

 to the inventor of the ubiquitous double glass dish, and may 

 have assumed, as I have, that the form of the name indicated 

 an Italian origin. About a year ago I had occasion to inquire 

 more particularh- just when and why this supposed Italian 

 invented his useful appliance. 



First, I turned to the Encyclopaedia Brittanica, in full 

 confidence that I should find there the neccessary details, 

 but there was not a word. In surprise, I scanned the pages 

 of other encyclopaedias at the Public Library at 42nd St., 

 looking through editions brought out in America, England, 

 German}', Italy, France, and Norway, but without finding 

 mention of any special dish. Petris there were common enough. 

 A certain Olaus Petri, a Swedish theologist, received most 

 space, but there were Germans of the same name, Dutch, 

 Italian, Swiss, and in the English forms, Petries and Petrys. 

 Finally, about tenth in the sequence of different encyclo- 

 paedias, I found in the Spanish "Encyclopaedia Universal 

 Illustrada" a brief reference to R. J. Petri as a German bac- 

 teriologist, but with no reference to any particular apparatus 

 perfected by him. For an exact reference to the original 

 description of the "Petri" dish I am indebted to Dr. George M. 

 Reed of the Brooklyn Botanic Garden. This first description 

 of the apparatus is brief, and, considering its wide use, is 

 well worth reprinting in translated form in full. 



"A slight modification of Koch's plating method."' 



"In order to make gelatin plates according to Koch's method, 

 it is necessary as is well known, to use the horizontal, once- 



1 Petri, R.J. "Eine kleine Modification des Koch'schen Methoden Platten- 

 verfahrens." Centralbiatt for Bacteriologie (Abt. 1. Band) 1: 279, 280. 

 1887. 



